The present invention relates to the preparation and use of thallium palladate as a new electrochemical active substance for the cover layer of metal anodes.
Certain patents and patent applications, e.g. German Democratic Republic Pat. No. 55,323, German Democratic Republic Pat. No. 77,963, German Published Application No. 1,671,422, German Published Application No. 1,917,040, German Published Application No. 1,813,944, German Published Application No. 1,962,860, and German Published Application No. 2,200,500 disclose metal anodes containing cover layers of the most varying composition in order to eliminate the drawbacks of the anode carrier members of passivatable metal, such as titanium, tantalum, zirconium, niobium, etc.
Most of the above substances, however, suggested for application as cover layer or as essential component thereof have unfortunately turned out to be disadvantageous, because their electrical conductivity and/or their chemical and electrochemical stability is not satisfactory or, respectively, a number of the suggested substances cannot at all or not very easily be applied to the anode carrier member without adversely affecting the requirements made respecting a cover layer.
Whereas for example alkaline earth palladates such as CaPd.sub.3 O.sub.4, SrPd.sub.3 O.sub.4 and NaPd.sub.3 O.sub.4 could already be synthesized in pure crystalline form, a preparation and adequate characterization of TlPd.sub.3 O.sub.4 was impossible till now.